Abstract: A hydraulic rock drill comprises a housing having a piston and valve bore formed therein, a rotation motor, and a fluid connection and fluid reservoir interposed between the housing and the rotation motor. Fluid connections to the hydraulic rock drill comprise a single inlet fluid connection to the housing and a single exhaust fluid connection from the rotation motor. The working shoulder areas of the piston are proportioned so that the exhaust stroke of the piston will pressurize the fluid in the reservoir, providing a fluid inlet source for the rotation motor. When the rotation torque demand increases, pressure in the fluid reservoir and pressure in the fluid inlet connection will rise accordingly, thus providing higher rotation torque while maintaining impact power. When fluid inlet pressure reaches a predetermined limit, rotation and impact will lessen or cease altogether.

Abstract: A simple and positive drill steel retainer comprises a retainer and a latch. The retainer cannot be opened until the latch is disengaged. The latch is held in the engaged position by a spring. The retainer and latch can be easily operated with one hand.